I remapped my Caps Lock key to switch into a "Greek" mode for typing, since I frequently need to type Greek letters interspersed with English. (Anybody in STEM classes should know how awkward it is to do this normally.) If you have a Mac, you can do this with Ukelele, a free key remapping tool. You can even set up and add "dead key" modes (e.g. the way opt+E allows you to add a diacritic to the next letter typed). There are some really advanced configurations possible. Ukelele even still works on Mavericks.
Not awkward, just with a little steep learning curve.
The only way to type math notation (which isn't the same character set as Greek. Compare \varepsilon with \epsilon, for example: http://www.w3.org/2003/entities/2007doc/#epsilon) is LaTeX. And for that, the only keys you really need are the dollar sign and backwards-slash.
I haven't set it up since getting a new laptop, but I used to have lots of math notation available on my keyboard (e.g. AltGr, <, = would give ≤), and LaTeX set up so that I could put those characters directly in my documents, and it was so much nicer than doing everything with backslash.
You'd find that STEM professionals (and academics, as some would say those two sets are disjoints) simply write LaTeX in their mails; I even find myself saying it when conversing face to face (but you loose the slashes: "take varepsilon less than frac x over y").
That's one big strength of LaTeX: everybody (in certain professions) knows it, so it is easy to collaborate on LaTeX typeset documents.
Well, as a Greek, typing Greek isn't hard at all. Install the Greek keyboard layout (should be a few clicks in any OS) , switch to it and the letters should more or less make sense (a is α, e is ε, i is ι, etc).
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